Pretty Print JSON generated with a jbuilder template in Rails 3.2.8

Question

Anyone have a way to pretty print JSON output from jbuilder?

I can pretty print JSON generated within a controller action with something like:

JSON.pretty_generate(some_json_object) 

but once I pass off to a jbuilder template, I'm not aware of a way to have that output pretty printed.

Right now, my action method's render statement is simple:

render formats: :json    

And this successfully forces a rendering with jbuilder, regardless of input format type specified (which is my desired behavior).

Answer 1

I think this is simpler,

@package = Package.first

json = JSON.parse(@blog.to_json)

PP.pp(json)

{"id_to_s"=>"5222675dbc11149e3a000002",
 "title"=>"Package Title",
 "version"=>"0.1.1",
 "comment"=>
  {"user"=>"Joe",
   "description"=>"Joe's comment"},
 "assets"=>
  [{"id_to_s"=>"522a4620fa451436f4000001",
    "_type"=>"Illustration",
    "start"=>0,
    "stop"=>100,
    "caption"=>"mountain climbing"},
   {"id_to_s"=>"522a56a6fa4514523a000001",
    "_type"=>"Illustration",
    "start"=>200,
    "stop"=>300,
    "caption"=>"airport"},
   {"id_to_s"=>"522a6a0ffa4514a30e000002",
    "_type"=>"Illustration",
    "start"=>400,
    "stop"=>600,
    "caption"=>"doc"},
   {"id_to_s"=>"522aa46bbc1114551f000001",
    "_type"=>"Illustration",
    "start"=>nil,
    "stop"=>nil,
    "caption"=>nil},
   {"id_to_s"=>"522aa47fbc1114551f000002",
    "_type"=>"Illustration",
    "start"=>10,
    "stop"=>30,
    "caption"=>"asdflkjsd"}]}

Or, the quicker one-liner,

PP.pp JSON.parse Blog.first.to_json

Answer 2

I found a way to do this:

 json_string = render_to_string formats: :json    
 json_object = JSON.parse(json_string)     
 render :json => JSON.pretty_generate(json_object)     

Again, this assumes there is a jbuilder template for this action, which will create the initial json, which gets rendered to a string, back into a json object and then passed to pretty_generate().

It's a bit circuitous, but it works. I'm of course, totally open to tighter implementations!

Answer 3

# config/initializers/jbuilder_prettify.rb
require "jbuilder"

class Jbuilder
  ##
  # Allows you to set @prettify manually in your .jbuilder files. 
  # Example: 
  #   json.prettify true
  #   json.prettify false 
  #  
  attr_accessor :prettify

  alias_method :_original_target, :target!

  ##
  # A shortcut to enabling prettify.
  # Example:
  #   json.prettify!
  #
  def prettify!
    @prettify = true
  end

  def target!
    @prettify ? ::JSON.pretty_generate(@attributes) : _original_target
  end
end

---

# app/views/api/v1/users/show.json.jbuilder
json.prettify! if %w(1 yes true).include?(params["pretty"])

json.( @user, :id, :name, :created_at, :updated_at )

https://github.com/rails/jbuilder/issues/195#issuecomment-44440569

Answer 4

Expanding on Blake Miller's answer...

Here is the code from the gist:

require 'multi_json'
MultiJson.use :yajl
unless Rails.env.production?
  MultiJson.dump_options = {:pretty=>true}
end

I put this into a file called /config/initializers/jbuilder_prettify.rb

In order for this to work you must have the yajl-ruby gem included in your Gemfile. Note that the jbuilder github homepage mentions here how using something like yajl-ruby will speed up your json rendering.

Answer 5

This worked for me, while the accepted answer did not. It's also shorter!

https://gist.github.com/jmoe/02c7476adac24eddd969

require 'multi_json'
MultiJson.use :yajl
unless Rails.env.production?
  MultiJson.dump_options = {:pretty=>true}
end